Effects of Straw Carbon Types on Fungal Community Characteristics of Soil Aggregates
[Objective]Fungal decomposition plays a key role as the primary driving force of the nutrient cycling and energy flow in the soil.However,the response characteristics of fungal communities to different types of straw carbon inputs and the key environmental factors at the aggregate scale are not yet clear.[Method]In this study,corn straw was used as the experimental,and three treatments were set according to the equal carbon content of straw returning:regular crushed straw(RS),decomposed straw(DS)and straw biochar(BC).A control group without straw application(CK)was also set up.The study aimed to investigate the effects of different carbon types from straws on the diversity,composition,and distribution of fungi in soil macroaggregates(>0.25 mm)and microaggregates(<0.25 mm),as well as the interactions within fungal communities.Furthermore,key environmental factors influencing the variation of soil fungal communities were explored.[Result]The results of a 2-year field experiment indicate that RS treatment significantly reduced fungal α diversity(P<0.05)in microaggregates(<0.25 mm)and macroaggregates(>0.25 mm).The top three dominant phyla in each treatment were Ascomycota,Mortierellomycota,and Basidiomycota,while the top three dominant genera were Plectosphaerella,Chaetomium,and Mortierella.Compared to different aggregate size fractions,the treatment with straw carbon significantly induced differentiation in fungal community structure(P<0.01),with notably distinct fungal community structure observed in the RS treatment compared to the other treatments.Also,analysis of fungal co-occurrence network showed that BC treatment increased the number of nodes(10.08%)and modularity(5.55%)while DS treatment increased the number of nodes(11.17%),the number of edges(32.57%)and the average degree of nodes(19.27%)included in the co-occurrence network,and all of which improved the structural stability of the fungal network of soil aggregates.The Mantel test analysis found that ammonium nitrogen(AN)and pH were the key environmental factors affecting the fungal community structure of soil aggregates,with the fungal community in the RS treatment being the most influenced by soil environmental factors.The prediction analysis of fungal community function showed that the input of straw carbon could reduce the relative abundance of pathogenic fungi and reduce the occurrence of soil-borne diseases in farmland.[Conclusion]Our results reveal that in the short term,different soil aggregates of fungi are more susceptible to the influence of straw carbon types,leading to differentiation.The addition of decomposed straw and straw biochar can increase soil AN content,thereby increasing the complexity of the fungal network,thus,promoting fungal community stability.Therefore,for practical applications,it is advisable to consider appropriately increasing the input of decomposed straw or straw biochar to promote the stability of soil ecological functions.
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